Contagious Bovine Pleuropneumonia: Key Facts And Control

Contagious bovine pleuropneumonia (CBPP) stands as one of the most serious infectious diseases impacting cattle populations, particularly in regions where it remains endemic. Caused by the bacterium Mycoplasma mycoides subsp. mycoides, this condition leads to severe inflammation of the lungs and pleura, resulting in significant economic losses through mortality, reduced productivity, and trade restrictions.

The Pathogen Behind CBPP

The causative agent, Mycoplasma mycoides subsp. mycoides (often abbreviated as Mmm), is a wall-less bacterium belonging to the mycoplasma family. Unlike many bacteria, mycoplasmas lack a cell wall, making them resistant to certain antibiotics like beta-lactams. This pathogen specifically targets cattle and water buffalo, thriving in the respiratory tract after inhalation.

Mmm adheres to the host’s airway epithelial cells, initiating colonization. This adhesion is highly specific to bovine respiratory tissues, allowing the bacterium to invade deeper lung structures. Once established, it triggers an intense inflammatory response, characterized by fibrinous exudates that consolidate lung tissue.

Global Distribution and Economic Impact

CBPP is notifiable to the World Organisation for Animal Health (WOAH), reflecting its status as a transboundary animal disease. While eradicated from most parts of the world through strict control measures, it persists in sub-Saharan Africa, where it causes substantial losses. In these regions, high morbidity and mortality rates—up to 50% in untreated acute cases—devastate herds, leading to decreased milk production, weight loss, and culling.

Historically, CBPP has been a barrier to livestock trade. Outbreaks in non-endemic areas, like Europe and North America, trigger immediate quarantines and stamping-out policies. In Africa, annual losses are estimated in millions due to direct animal deaths and indirect effects like reduced market access.

How CBPP Spreads in Herds

Transmission occurs primarily through aerosols—droplets expelled by coughing infected animals. Direct nose-to-nose contact facilitates close-range spread, especially in confined settings like feedlots or markets. Infected cattle shed the bacterium in respiratory secretions, saliva, urine, and even fetal fluids, with transplacental infection possible in pregnant cows.

Carrier animals pose a significant challenge, as they may appear healthy yet harbor the pathogen in lung sequestra—walled-off areas of infected tissue. Stress can reactivate shedding, perpetuating silent transmission. The incubation period ranges from 2-8 weeks, sometimes extending to 6 months, allowing undetected spread during animal movements.

• Aerosol droplets from coughs: Primary route in close-contact herds.
• Direct contact with secretions: Saliva, nasal discharge, urine.
• Vertical transmission: From dam to calf in utero.
• No fomite or environmental persistence: Limits indirect spread.

Recognizing Clinical Manifestations

CBPP presents in acute, subacute, and chronic forms, with symptoms varying by disease stage and host factors. Acute cases dominate epidemics, featuring high fever (up to 42°C), anorexia, and pronounced respiratory distress.

Affected cattle often isolate themselves, standing with extended necks, abducted elbows, and open-mouth breathing. Coughing produces frothy mucus, and painful respiration leads to grunting. Without intervention, death occurs in 1-3 weeks, with mortality reaching 50%.

Calves under 6 months may develop arthritis rather than pneumonia, showing lameness. Recovered animals gain immunity but can relapse under stress.

Pathological Changes in Affected Lungs

Gross pathology reveals marbled lungs with hepatized, fibrin-covered areas and pleural effusion—straw-colored fluid in the thoracic cavity. Chronic cases form sequestra: necrotic lung pockets encapsulated by fibrous tissue, serving as bacterial reservoirs.

Microscopically, fibrinonecrotic bronchopneumonia predominates, with lymphocytic infiltration and hyperplasia of bronchial-associated lymphoid tissue. These lesions impair gas exchange, exacerbating respiratory failure.

Diagnostic Approaches for Confirmation

Diagnosis combines clinical suspicion, history of exposure, and laboratory tests. Post-mortem examination shows characteristic lesions: interlobular edema, fibrin tags, and sequestra.

1. Culture and isolation: Gold standard, growing Mmm on special media.
2. PCR: Detects Mmm DNA rapidly from swabs or tissues.
3. Serology: cELISA for antibodies; differentiates carriers.
4. Clinical pathology: Thoracentesis yields fibrinous fluid.

In live animals, ultrasound reveals pleural effusion and lung consolidation. Differential diagnoses include pasteurellosis, lungworm, or viral pneumonias.

Treatment Options and Limitations

Antibiotics like oxytetracycline or tylosin offer partial control in early stages but fail against chronic sequestra. Treatment reduces mortality but doesn’t eliminate carriers, risking herd spread. In endemic areas, it’s used palliatively alongside vaccination.

Dual therapy (e.g., oxytetracycline plus tylvalosin) improves outcomes, but resistance emerges. Severely affected animals often require euthanasia.

Vaccination and Preventive Strategies

The T1/44 live attenuated vaccine provides 60-80% protection but wanes after 6-12 months, necessitating annual boosts. It’s risky in calves and pregnant cows, with occasional reversion to virulence reported. Newer subunit vaccines are under development.

Control emphasizes biosecurity: quarantine, movement controls, and stamping-out in outbreaks. Test-and-slaughter targets carriers. In Africa, integrated approaches combine vaccination, treatment, and surveillance.

Frequently Asked Questions (FAQs)

What animals are susceptible to CBPP?

Cattle and water buffalo are primary hosts; other bovids like yaks are less affected. Small ruminants and wildlife do not transmit.

Can CBPP spread to humans?

No, it’s strictly a bovine pathogen with no zoonotic potential.

How long do infected cattle remain contagious?

Up to 6 months or longer in carriers with lung sequestra.

Is CBPP eradicated worldwide?

No, endemic in sub-Saharan Africa; eradicated elsewhere via strict measures.

What is the role of WOAH in CBPP control?

WOAH lists CBPP as notifiable, providing standards for surveillance, diagnosis, and trade.

Future Directions in CBPP Management

Ongoing research focuses on improved diagnostics like pen-side tests, safer vaccines (e.g., recombinant proteins targeting adhesins), and genomic sequencing for strain tracking. Climate change and pastoralism complicate control in Africa, urging One Health approaches integrating veterinary and public health.

Global collaboration via WOAH and FAO aims to reduce CBPP’s burden, potentially eradicating it from endemic zones through sustained vaccination and trade hygiene.